1. Field of the Invention
This present invention concerns a device and Photodynamic therapy (PDT) method for treating cancerous conditions in humans. In particular, this invention relates to high power Light Emitting Diode (LED) based photonic device for treating hyper-proliferative cell conditions related to gynecology problems in humans and animals.
2. Invention Disclosure Statement
The photodynamic therapy (or PDT) method involves administration of photosensitizer followed by application of light energy. Photo activated photosensitizer generates photo oxidation for tissue destruction. PDT is used for treating hyper-proliferative cell conditions in humans and animal. The main differences between PDT and other tumour therapies, like chemotherapy and radiotherapy, are its localized and controllable effectiveness. The limited penetration of light into tissue can be used to treat superficial tumors without damaging delicate structures situated below the diseased area, which are often at risk in radiotherapy.
PDT has been clinically used to treat metastatic breast cancer, bladder cancer, lung carcinomas, oesophageal cancer, basal cell carcinoma, malignant melanoma, ocular tumors, head and neck cancers, and other types of malignant tumors. Because PDT is selective in destroying abnormal cells that have absorbed more of the photosensitizer, than normal cell can, thus it can successfully be used to kill malignant tissue with less effect on surrounding cells in critical areas.
Two of the parameters controlling the efficacy of PDT are the intensity and total amount of the light received by the treated tissue. Because of scattering of light by the tissue a field of diffuse light is received by the tissue, consisting of the original incident light plus light scattered from other irradiated areas. Irradiation with appropriate wavelength for a given photosensitizer may be administered by variety of methods.
PDT methods provide a minimally invasive procedure for treating gynecological problems without needing anesthesia. Dysplasia is abnormal growth of the cells. Dysplasia of cervix and portio is a term used to describe the appearance of abnormal cells on the surface of the cervix, the lowest part of the uterus. It can range from mild to moderate or severe depending on the spread of the abnormal cells. While dysplasia itself does not cause health problems, it is considered to be a precancerous condition. When left untreated, dysplasia sometimes progresses to an early form of cancer known as cervical carcinoma in situ, and eventually to invasive cervical cancer. Dysplasia occurs in females aged 15 and over, and most often in those in 25 to 35 age group. Experimental and epidemiologic data suggest that certain subtypes of human papilloma virus (HPV) play an etiologic role in the development of cervical carcinoma by transforming epithelial cells into precancerous cells.
The reported incidence of cervical dysplasia every year is approximately between 250,000 and 1 million women in the United States alone. Most dysplasia cases can be cured with early diagnosis, proper treatment and follow-up. Without treatment, 30% to 50% may progress to invasive cancer.
Presently available treatment methods include medication, electro-cauterization, cryosurgery, laser vaporization, and surgery. In cryotherapy the cervix is cooled to sub zero temperature thus damaging the cells by freezing them. The main advantage of this method is it is simple and inexpensive. A main disadvantage is, it cannot freeze the abnormal cell seated deep below and are thus left behind untreated. Thus is not suitable to treat large and severe conditions of dysplasia.
Loop excision is another conventional method wherein the tissue is removed by a loop of wire. Also known as LEEP (loop electrosurgical excision procedure), loop excision uses a fine wire loop with electrical energy flowing through it to remove the abnormal area of the cervix. Cramping is common during the procedure, and light bleeding is expected.
In the cone biopsy method a cone of tissue is removed from in and around the cervix either by surgery or by using a laser. This procedure requires anesthesia and is carried out in a surgical setting. Light bleeding and discomfort is common after the procedure.
Hysterectomy is another option but this can be done in women who do not want to bear children in future. It has the lowest recurrence rate of any treatment, but it is a major surgical procedure. Even after a hysterectomy the dysplasia can come back on the vagina, so it is essential to get regular pap smears even if a hysterectomy is done. Most of all it is not suitable for women in child bearing age group.
In laser therapy, carbon dioxide laser is used to vaporize the abnormal cells. The laser is directed through the colposcope so that normal cells are not affected and the laser is directed precisely at the affected region. Healing after laser treatment is much faster than after freezing because dead tissue is not left behind. Studies using the latest techniques of laser treatment are showing lower failure rates with the laser than with freezing. Another important advantage is that the cervix usually heals with the squamo-columnar junction visible, so that future evaluation is easily carried out.
The major disadvantage of the laser therapy is that it requires sophisticated equipment, and most gynecologists do not have a laser in their office. It is much more expensive to do laser if it has to be done in the hospital. All these methods are not very effective for treating invasive cancers.
Although most of these methods are effective to some extent in treating dysplasia, unfortunately, it can be detrimental to fertility and normal childbearing process. In an attempt to encircle all abnormal tissue and the transformation zone of the endocervical lining, the cervix may loose the ability to withstand the weight load of a normal gestation towards term. A solution to the incompetent cervix is surgical cerclage, which again carries high risk of failure, infection and detriment to future fertility. Additionally ablative techniques may leave behind residual microscopic abnormal tissue. This predicament is usually addressed by additional ablative treatments, further increasing damage to the cervix.
In WO 94/15666A1 a light emitting diode source for PDT application had been shown. Here a LED based light device with 660 nm wavelength, having a fluid cooling system has been disclosed. The device is designed to produce large surface area illumination, that can be used to treat certain dermatological problem and for other applications. Similarly in WO 93/21842A1 a high power light emitting diodes is presented for PDT applications. In this invention LED based apparatus are used for activating photosensitizers at a single wavelength band and uniform power density. The cancerous and other undesirable tissues or cells are directly illuminated using a suitably positioned LED device. Another example of LED based light delivery device for uniform surface illumination of tissues or cells is presented in U.S. Pat. No. 5,698,866. Most of the LED based light applicators used in the prior art are designed for surface illumination and for treating dermatological problems. None of these devices are suitable for treating the cervical dysplasia.
In the present invention a photonic based device is presented which is less expensive, compact and easier to handle compared to laser. The present invention aims at providing a suitably designed applicator and a PDT method for treating cervix and other portion of the body where abnormal cells growth is reported. The present method overcomes the drawback reported in current treatment methods.